I thought of you and your BAT on Friday, in fact -- I was climbing at Curbar and when we got onto a ledge there was OUTRAGED SHOUTING from inside the route next to us. A crow's nest, I'm guessing, but it must have had multiple fairly big fledglings, because SO MUCH SHOUT.

(Crows are not frightened off by climbers. There's one route at Stoney Middleton where you can look through the online logbook entries at UKClimbing.com and track through the comments how many years the crows have been nesting in it. Apparently if they have fledglings, the adults will throw sticks at you.)

(ETA: years and years of comments going OH GOD THE CROWS THE CROWS)